--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2026 Christian Brauner <brauner@kernel.org>
+/*
+ * Test extended attributes on sockfs sockets.
+ *
+ * Sockets created via socket() have their inodes in sockfs, which supports
+ * user.* xattrs with per-inode limits: up to 128 xattrs and 128KB total
+ * value size. These tests verify xattr operations via fsetxattr/fgetxattr/
+ * flistxattr/fremovexattr on the socket fd, as well as limit enforcement.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/xattr.h>
+#include <unistd.h>
+
+#include "../../kselftest_harness.h"
+
+#define TEST_XATTR_NAME "user.testattr"
+#define TEST_XATTR_VALUE "testvalue"
+#define TEST_XATTR_VALUE2 "newvalue"
+
+/* Per-inode limits for user.* xattrs on sockfs (from include/linux/xattr.h) */
+#define SIMPLE_XATTR_MAX_NR 128
+#define SIMPLE_XATTR_MAX_SIZE (128 << 10) /* 128 KB */
+
+#ifndef XATTR_SIZE_MAX
+#define XATTR_SIZE_MAX 65536
+#endif
+
+/*
+ * Fixture for sockfs socket xattr tests.
+ * Creates an AF_UNIX socket (lives in sockfs, not bound to any path).
+ */
+FIXTURE(xattr_sockfs)
+{
+ int sockfd;
+};
+
+FIXTURE_SETUP(xattr_sockfs)
+{
+ self->sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
+ ASSERT_GE(self->sockfd, 0) {
+ TH_LOG("Failed to create socket: %s", strerror(errno));
+ }
+}
+
+FIXTURE_TEARDOWN(xattr_sockfs)
+{
+ if (self->sockfd >= 0)
+ close(self->sockfd);
+}
+
+TEST_F(xattr_sockfs, set_get_user_xattr)
+{
+ char buf[256];
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("fsetxattr failed: %s", strerror(errno));
+ }
+
+ memset(buf, 0, sizeof(buf));
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, (ssize_t)strlen(TEST_XATTR_VALUE)) {
+ TH_LOG("fgetxattr returned %zd: %s", ret, strerror(errno));
+ }
+ ASSERT_STREQ(buf, TEST_XATTR_VALUE);
+}
+
+/*
+ * Test listing xattrs on a sockfs socket.
+ * Should include user.* xattrs and system.sockprotoname.
+ */
+TEST_F(xattr_sockfs, list_user_xattr)
+{
+ char list[4096];
+ ssize_t ret;
+ char *ptr;
+ bool found_user = false;
+ bool found_proto = false;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("fsetxattr failed: %s", strerror(errno));
+ }
+
+ memset(list, 0, sizeof(list));
+ ret = flistxattr(self->sockfd, list, sizeof(list));
+ ASSERT_GT(ret, 0) {
+ TH_LOG("flistxattr failed: %s", strerror(errno));
+ }
+
+ for (ptr = list; ptr < list + ret; ptr += strlen(ptr) + 1) {
+ if (strcmp(ptr, TEST_XATTR_NAME) == 0)
+ found_user = true;
+ if (strcmp(ptr, "system.sockprotoname") == 0)
+ found_proto = true;
+ }
+ ASSERT_TRUE(found_user) {
+ TH_LOG("user xattr not found in list");
+ }
+ ASSERT_TRUE(found_proto) {
+ TH_LOG("system.sockprotoname not found in list");
+ }
+}
+
+TEST_F(xattr_sockfs, remove_user_xattr)
+{
+ char buf[256];
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fremovexattr(self->sockfd, TEST_XATTR_NAME);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("fremovexattr failed: %s", strerror(errno));
+ }
+
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENODATA);
+}
+
+TEST_F(xattr_sockfs, update_user_xattr)
+{
+ char buf[256];
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE2, strlen(TEST_XATTR_VALUE2), 0);
+ ASSERT_EQ(ret, 0);
+
+ memset(buf, 0, sizeof(buf));
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, (ssize_t)strlen(TEST_XATTR_VALUE2));
+ ASSERT_STREQ(buf, TEST_XATTR_VALUE2);
+}
+
+TEST_F(xattr_sockfs, xattr_create_flag)
+{
+ int ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE2, strlen(TEST_XATTR_VALUE2),
+ XATTR_CREATE);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, EEXIST);
+}
+
+TEST_F(xattr_sockfs, xattr_replace_flag)
+{
+ int ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE),
+ XATTR_REPLACE);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENODATA);
+}
+
+TEST_F(xattr_sockfs, get_nonexistent)
+{
+ char buf[256];
+ ssize_t ret;
+
+ ret = fgetxattr(self->sockfd, "user.nonexistent", buf, sizeof(buf));
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENODATA);
+}
+
+TEST_F(xattr_sockfs, empty_value)
+{
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME, "", 0, 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, NULL, 0);
+ ASSERT_EQ(ret, 0);
+}
+
+TEST_F(xattr_sockfs, get_size)
+{
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, NULL, 0);
+ ASSERT_EQ(ret, (ssize_t)strlen(TEST_XATTR_VALUE));
+}
+
+TEST_F(xattr_sockfs, buffer_too_small)
+{
+ char buf[2];
+ ssize_t ret;
+
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ERANGE);
+}
+
+/*
+ * Test maximum number of user.* xattrs per socket.
+ * The kernel enforces SIMPLE_XATTR_MAX_NR (128), so the 129th should
+ * fail with ENOSPC.
+ */
+TEST_F(xattr_sockfs, max_nr_xattrs)
+{
+ char name[32];
+ int i, ret;
+
+ for (i = 0; i < SIMPLE_XATTR_MAX_NR; i++) {
+ snprintf(name, sizeof(name), "user.test%03d", i);
+ ret = fsetxattr(self->sockfd, name, "v", 1, 0);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("fsetxattr %s failed at i=%d: %s",
+ name, i, strerror(errno));
+ }
+ }
+
+ ret = fsetxattr(self->sockfd, "user.overflow", "v", 1, 0);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENOSPC) {
+ TH_LOG("Expected ENOSPC for xattr %d, got %s",
+ SIMPLE_XATTR_MAX_NR + 1, strerror(errno));
+ }
+}
+
+/*
+ * Test maximum total value size for user.* xattrs.
+ * The kernel enforces SIMPLE_XATTR_MAX_SIZE (128KB). Individual xattr
+ * values are limited to XATTR_SIZE_MAX (64KB) by the VFS, so we need
+ * at least two xattrs to hit the total limit.
+ */
+TEST_F(xattr_sockfs, max_xattr_size)
+{
+ char *value;
+ int ret;
+
+ value = malloc(XATTR_SIZE_MAX);
+ ASSERT_NE(value, NULL);
+ memset(value, 'A', XATTR_SIZE_MAX);
+
+ /* First 64KB xattr - total = 64KB */
+ ret = fsetxattr(self->sockfd, "user.big1", value, XATTR_SIZE_MAX, 0);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("first large xattr failed: %s", strerror(errno));
+ }
+
+ /* Second 64KB xattr - total = 128KB (exactly at limit) */
+ ret = fsetxattr(self->sockfd, "user.big2", value, XATTR_SIZE_MAX, 0);
+ free(value);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("second large xattr failed: %s", strerror(errno));
+ }
+
+ /* Third xattr with 1 byte - total > 128KB, should fail */
+ ret = fsetxattr(self->sockfd, "user.big3", "v", 1, 0);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENOSPC) {
+ TH_LOG("Expected ENOSPC when exceeding size limit, got %s",
+ strerror(errno));
+ }
+}
+
+/*
+ * Test that removing an xattr frees limit space, allowing re-addition.
+ */
+TEST_F(xattr_sockfs, limit_remove_readd)
+{
+ char name[32];
+ int i, ret;
+
+ /* Fill up to the maximum count */
+ for (i = 0; i < SIMPLE_XATTR_MAX_NR; i++) {
+ snprintf(name, sizeof(name), "user.test%03d", i);
+ ret = fsetxattr(self->sockfd, name, "v", 1, 0);
+ ASSERT_EQ(ret, 0);
+ }
+
+ /* Verify we're at the limit */
+ ret = fsetxattr(self->sockfd, "user.overflow", "v", 1, 0);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENOSPC);
+
+ /* Remove one xattr */
+ ret = fremovexattr(self->sockfd, "user.test000");
+ ASSERT_EQ(ret, 0);
+
+ /* Now we should be able to add one more */
+ ret = fsetxattr(self->sockfd, "user.newattr", "v", 1, 0);
+ ASSERT_EQ(ret, 0) {
+ TH_LOG("re-add after remove failed: %s", strerror(errno));
+ }
+}
+
+/*
+ * Test that two different sockets have independent xattr limits.
+ */
+TEST_F(xattr_sockfs, limits_per_inode)
+{
+ char buf[256];
+ int sock2;
+ ssize_t ret;
+
+ sock2 = socket(AF_UNIX, SOCK_STREAM, 0);
+ ASSERT_GE(sock2, 0);
+
+ /* Set xattr on first socket */
+ ret = fsetxattr(self->sockfd, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE, strlen(TEST_XATTR_VALUE), 0);
+ ASSERT_EQ(ret, 0);
+
+ /* First socket's xattr should not be visible on second socket */
+ ret = fgetxattr(sock2, TEST_XATTR_NAME, NULL, 0);
+ ASSERT_EQ(ret, -1);
+ ASSERT_EQ(errno, ENODATA);
+
+ /* Second socket should independently accept xattrs */
+ ret = fsetxattr(sock2, TEST_XATTR_NAME,
+ TEST_XATTR_VALUE2, strlen(TEST_XATTR_VALUE2), 0);
+ ASSERT_EQ(ret, 0);
+
+ /* Verify each socket has its own value */
+ memset(buf, 0, sizeof(buf));
+ ret = fgetxattr(self->sockfd, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, (ssize_t)strlen(TEST_XATTR_VALUE));
+ ASSERT_STREQ(buf, TEST_XATTR_VALUE);
+
+ memset(buf, 0, sizeof(buf));
+ ret = fgetxattr(sock2, TEST_XATTR_NAME, buf, sizeof(buf));
+ ASSERT_EQ(ret, (ssize_t)strlen(TEST_XATTR_VALUE2));
+ ASSERT_STREQ(buf, TEST_XATTR_VALUE2);
+
+ close(sock2);
+}
+
+TEST_HARNESS_MAIN
projects / thirdparty / kernel / linux.git / commitdiff
